A light emitting diode (LED) is a semiconductor device that emits light of various colors based on electron-hole recombination which occurs at a p-n junction between p-type and n-type semiconductors when current is applied to the LED. Compared to a filament-based light emitting device, LED devices have several advantages such as increased longevity, lower power consumption, superior initial-operating characteristics, and high vibration resistance. These factors have continually increased demand for LEDs. Recently, much attention has been directed to group III nitride semiconductors which emit light in a blue/short wavelength region.
Nitride semiconductor crystals, which are part of light emitting devices that use group III nitride semiconductor, are grown on a sapphire or SiC substrate. In order to grow these semiconductor crystals, a plurality of gas-state sources are deposited on the substrate by a vapor deposition process. The light emission performance and reliability of a semiconductor light emitting device may be significantly affected by the quality of semiconductor layers (such as crystallinity). Therefore, the quality of semiconductor layers may depend on the structure, internal environment and usage conditions of a vapor deposition apparatus used for the growth of semiconductor thin films. Thus, a need exists for a method of improving the quality of semiconductor layers by improving and optimizing the vapor deposition process.